1. Field of the Invention
The present invention relates to the teaching of skills needed to interpret and prepare mechanical drawings. In particular, the present invention relates to an apparatus for teaching the interpretation and preparation of isometric views and orthographic projections of objects.
2. Discussion of Background
Mechanical drawings known as "working drawings" provide the information needed for construction of each part of a manufactured product and for the correct assembly of the finished product. Without drawings, it would be difficult, if not impossible, to describe a product in sufficient detail for a skilled technician to accurately construct the product.
In order to understand the information in a working drawing, a person must be able to "read" the drawing, that is, interpret it well enough to visualize the three-dimensional object shown in the two-dimensional drawing. Commonly-used working drawings include isometric views and orthographic projections. In an isometric view, also known as an axonometric projection, the object being drawn is turned so that three mutually perpendicular edges are equally foreshortened. Isometric views are usually constructed with the height along the vertical axis, and the front (width) and right side (depth) projected at angles of 30 degrees from the horizontal so that the front slants up-left and the right side slants up-right. Every surface on an isometric view represents either a top, a front, or a right side. Thus, the object looks about the same as it would in a photograph, which is a two dimensional representation or reproduction of a three-dimensional object, with the dimensions of the object shown in proportion.
An orthographic projection shows separate two-dimensional views of three sides of the object, with each view shown as if the viewer was looking at that side, straight-on, at eye level. The most common views used are the top, front and fight side, arranged in a systematic way to assist the person who is reading the views to visualize the object. Experienced viewers are able to visualize a three-dimensional object by systematically examining the three two-dimensional orthographic projections.
Students learn to prepare and interpret mechanical drawings by practicing a variety of tasks, including copying previously-executed drawings, preparing isometric views and orthographic projections of three-dimensional models, and preparing isometric views from orthographic projections and vice versa. The lessons in a typical course of instruction are presented in a predetermined order, with successive lessons involving more advanced and difficult concepts.
A number of devices are known for teaching drawing, including drawing kits for creating perspective drawings from projections (Cutler, U.S. Pat. No. 5,100,325), and various educational toys (Frisque, U.S. Pat. No. 5,080,590; Hankins, U.S. Pat. No. 4,306,868; Redey, U.S. Pat. No. 2,835,987). Drawing aids include a mechanical drawing guide (Heiser, U.S. Pat. No. 2,835,987), adhesive shapes for use as a computer logic design aid (Griffin, et al., U.S. Pat. No. 4,696,706), and magnetic objects placed on a metal surface with a set of grid lines (Ihms, U.S. Pat. No. 3,851,394). Rinehuls (U.S. Pat. No. 3,590,499) uses three colors to identify the top, front and side of the shapes in his mechanical drawing kit, and Redey (U.S. Pat. No. 2,977,688) combines objects with standard shapes to make front, side and top views against a three-sided, grid-lined chart.
The ability to visualize and interpret geometric shapes varies widely among people, but may be improved by practice. Ideally, students are presented with a set of lessons involving successively more advanced and difficult concepts, and proceed to a next lesson only after mastering the concepts of the preceding lessons. However, different students progress at different rates, thus, it may be difficult for an instructor to teach all students in a class effectively. No known drawing kit provides the capability for self-paced learning combined with the capability for practicing a variety of different drawing-related tasks: preparing isometric views and orthographic projections of a three-dimensional object, preparing three-dimensional models from isometric views and/or orthographic projections, and preparing isometric views from orthographic projections and vice versa.